Aorta

The aorta is the largest artery of the body, it originates from the left ventricle of the heart and extends down to the abdomen where it branches out into smaller arteries. The aorta is an elastic artery with a thick wall of smooth muscle and elastic matrix. Besides smooth muscle, the aorta also includes nerves, endothelial cells, fibroblast-like cells and extracellular matrix. The different parts of the aorta can be divided into; tunica externa, tunica media and tunica intima.

Tunica intima is the innermost layer of the aorta, consisting of endothelial cell layer and a layer of elastic lamina. Tunica media is the middle layer and includes smooth muscle cells, collagen and elastic tissue creating concentric musculoelastic layers. The tunica externa, also called tunica adventitia, is the outer layer of aorta, which contains collagen and external elastic lamina as well as peripheral nerves, adipocytes and smaller blood vessels.